A Retrospective Study of 116 Multiple Sclerosis Patients with Dimethyl Fumarate Treatment in a Single Institution in Japan

Background The global prevalence of multiple sclerosis (MS) is increasing worldwide. Although many disease-modifying therapies (DMTs) have been approved, they can cause serious adverse events, including infections. Dimethyl fumarate (DMF), an immunomodulator, has a favorable safety profile. In this era of personalized therapy, it is important to select an appropriate DMT for individual patients. This study evaluated DMF treatment outcomes in Japanese patients with MS. Methods The medical records of Japanese patients with MS treated with DMF at a single institution between January 6, 2013, and October 31, 2022, were reviewed retrospectively. The reasons for discontinuation of DMF, switching from other DMTs to DMF, transition of DMF to other medications, absolute lymphocyte count, disease activity assessment, comparison of DMF continuation versus discontinuation, and factors associated with the annualized relapse rate during DMF use were assessed. Results Of the 116 DMF-treated patients, DMF treatment was continued to prevent relapse recurrence in 54.7% of RRMS (n=86) and 23.3% of SPMS (n=30) patients. The main reasons for not continuing DMF treatment included failure to prevent relapse or disease progression (63% of patients who did not continue DMF). A lower annual recurrence rate prior to DMF initiation, lower Expanded Disability Status Scale score, shorter duration from disease onset to DMF initiation, fewer relapse recurrences during DMF therapy, and diagnosis of RRMS were associated with DMF continuation. Conclusion Continuous monitoring is essential after initiating DMF treatment because patients may require transition to other therapies. Overall, 47% of the MS patients were effectively managed with DMF, with favorable outcomes observed in 54.7% of the RRMS patients.